The field of the invention is manually operable vents for closable containers.
Fuel tanks, fuel storage cans, or the like, require venting to allow gas to escape from the container when excess pressure builds up, and to allow air to enter the tank under negative pressure conditions. For some storage tanks, it is desirable to have the container completely sealed while not in use to prevent evaporation of the contents, to stop contaminants from entering, and to reduce the risk of spillage. However, even with such tanks, it is still desirable to permit venting at selected times (e.g. during the filling or emptying of the tank).
Some valves which permit this type of venting control do exist. However, it is desired to improve these values. Goals to be simultaneously achieved by such an improved valve are reducing the likelihood of the closure member becoming lost, reducing the likelihood of breakage of the closure member, reducing spillage potential, making reclosure easier, and avoiding the need for a complex and expensive construction.